Well safety valve



Aug. 9, 1966 G. H. TAUscH WELL SAFETY VALVE Filed Feb. 3. 1964 UnitedStates Patent O 3,265,134 WELL SAFETY VALVE Gilbert ll-l. Tausch,Houston, Tex., assigner to Camco, lncorporated, Houston, Tex., acorporation of Texas Filed Feb. 3, 1964, Ser. No. 341,914 6 Claims. (Cl.166-224) This invention relates to subsurface well tools land moreparticularly to an improved safety valve which shuts olf production ofwell fluid from an oifl or gas well and acts in response to pressuredrop above the valve as may result from Wild dow at a break or becauseof malfunctioning in the pipe system down stream of the self actingclosure valve.

An object of the invention is to provide an automatically operated valveto shut oif well production upon a system failure and Ito minimize thelikelihood of personal injury and equipment damage -as well as fire andloss of well fluids.

A further object is to provide a more reliable and simplied valve unitwhich is self contained without complicated and costly surfacecontrolled connections and which remains open under normal flowconditions in response to vthe action thereon of tube pressure exerteddownwardly and on unbalanced surface areas of a valve controlling slidetube and solely against mechanical spring force.

Another object is to provide a simple valve unit having a minimum numberof easily manufactured parts comprising an outer body larranged forconnection in a production tubing string and forme-d with an annularvalve seat for a swing valve mounted on the body, together with an innertube controlling swing valve operation by slide travel through theannular valve seat as governed by well pressure down stream thereof andactive on an exposed upwardly facing area of inner tube surface which inrelation to exposed downwardly facing inner tube surface area isunbalanced by a downwardly facing inner tube surface confined within asealed-olf chamber containing gas at ordinary atmospheric pressure.

Other objects and advantages will become apparent from the followingspecification having reference to the accompanying drawing wherein FIG.1 is a vertical sectional view of a :gas well installation including theimproved safety va-lve,'and FIG. 2 is a part elevational and partvertical section on a large scale of, the valve detail.

The valve unit 1 includes a pair of relatively slidable tubular members2 and 3 concentrically nested one within the other with axially spacedapart portions in sealed slide bearing engagement and with intermediateportions radially spaced apart to form aclosed annular chamber 4 whichis completely enclosed between the tubular members and sealed at itsends between the slide bearing portions of the tubes. For convenience ofmanufacture and assembly, each tubular member consists of a number ofseparately machined sections screw threaded together in end-to-endsuccession. As shown, the inner ytube 3 corn-v prises a top section 5whose wall is relatively thick, a thinner wall intermediate section 6and `a bottom section 7, all having the same internal diameter andproviding an unrestricted open bore through the unit. From top to bottomthe outer tube 2 comprises a relatively thick wall coupling section 8, athinner wall intermediate body section 9, another intermedi-ate bodysection 10 whose wall is somewhat thicker than the Wall of the couplingsection "ice 8 and a valve cage or terminal housing 11, all of thesesections of the outer tube having the same outside diameter.

Internal screw threads within the upper end of the coupling section 8lare for fastening the outer tubular body 2 as a unit with aconventional type of locating hanger 12 as is seen in FIG. 1 wherein thehanger 12 is latched at a selected depth within a well production tubingstring 13. The coupling section 8 also has an internal annular flangeshown at 14 in FIG. 1 as being immediately below the attachment threadsand this flange 14 provides a downwardly facing shoulder las an upperlimit stop to slide travel of the inner tubular member 3 when itsrelatively wide bearing end surface 21 on the top section 5 rises intoabutment with the shoulder 8.

In FIG. 2 the inner tube 3 is shown at its lower travel limit and withthe bottom edge of the intermediate section 6 in downward abutment on aninternal and upwardly facing annular shoulder at 15 on the outer tubingsection 10. Peripherally enlarged bands 16 and 17 on the inner tubularmembers 6 and 5 have a close sliding tit on interior cylindricalsurfaces of the outer tubing sections 10 and 8. Both cylindricalsurfaces are smoothly machined and each is of a length greater than thetravel range of their cooperating bearing bands 16 and 17. Both bandshave external `annular grooves to pocket elastic sealing rings 18 and 19for snug engagement on the bearing surfaces of sections 10 and 8 and forsealing oli the closed chamber 4 between the thin wall sections 6 and 9of the inner and outer tubes. At the time of iinal assembly of theparts, the chamber 4 will be sealed oif at atmospheric pressure andpreferably Within a room of relatively low humidity and the valve unitwill be substantially free of chamber pressurization when installed in aWell and will not be dependent in any sense on external sources ofvariable pressure for effective valve operation during its normal life.

A compression coil spring 20 enclosed within the atmospheric pressurechamber 4 is grounded at its llower end on the upper end of the thickbody section 10 and bears upwardly on the chamber confined lower endsurface of the inner tubular section 5. The force of the spring 20yieldably biases the inner tube 3 upwardly and against the downwardforce of tubing pressure above the valve and active on the exposed endsurface 21 of the inner tube when the unit is installed within aproduction tubing string and the well is producing fluid under normalconditions. Such tubing fluid pressure acting on the surface 21 willovercome the spring 20 and hold the inner tube 3 depressed to theposition illustrated in FIG. 2.

In such downwardly projected position the lower section 7 of the innertube extends below the bottom end of the outer tube section 10 and intothe path of and obstructs inward and upward swing travel of a flap valve22. The flap valve 22 depends from and is hingedly mounted on a pintlepin 23 secured at opposite ends in the wall of the terminal section 11.When free to close the flap valve seats upwardly against the lowerannular face of the tube section 10. For better insuring againstleakage, a rubber or similar gasket ring 24 is clamped within annulargroove in the bottom face of the member 10 and by an internal shoulderon the tube portion 11. The gasket ring 24 is shown 4as having aninwardly protruding Aannular lip as a facing to `overlap the valve seatand to be engaged by the ap Valve 22.

During normal operation of the well the ldap valve is held open and theproduced iluid leaves the well at the surface through a gathering line25 which may contain a control valve Vand a suitable ilow controlorifice or choke. In such operation no pressure drop occurs across theslide tube 3 and the fluid pressure acting on the differential areas ofdownwardly and upwardly :facing surfaces of the slide tube holds theslide tube at its downwardly retracted limi-t. Such upwardly facing areais constituted primarily by the relatively wide upper end face at 21exposed above the seal ring 19 and which face is of greater area `thanany downwardly facing area of the slide tube exposed below the seal 18and related in size to the narrow vvidth of the intermediate tubingsection 6.

Should breakage or a malfunction occur in the ilow 'line down streamfrom the valve unit, such as to release pressure and cause a pressuredrop at the safety valve unit, then the upward bias of the spring willelevate the inner tube 6 into engagement with the upper limit stop 8whereupon the bottom section 7 lwill be -above the valve sea-t and outof interference and blocking relation to the free inward and upwardswing of the diap valve I22. The flap valve will move up and be heldclosed by well fluid pressure beneath it to preserve the well fromrunning wild and until necessary remedial measures have been taken. Thecoil spring 20 provides `the sole force to shift the slide valveupwardly and .to oppose tubing pressure, since air confined inside thechamber at atmospheric pressure and the limited range of variation ofchamber sizel are insignificant in relation to the opposing spring andtubing pressures.

Extraneous pressure sources and complex controlled systems which oftenare troublesome are eliminated by the simple and low cast valvearrangement as herein described. Various modifications in the structuralIdetail are cornprehended as being within the scope of the attachedclaims.

What is claimed is:

1. A safety valve for installation in a well fluid production tubing,comprising an inner tube having an annular wall surrounding a full openstraight bore therethrough and said wall having peripherally thereof adownwardly facing shoulder joining vertically offset peripheral portionsof a relatively thick upper wall portion and a relatively thin lowerwall portion, an outer Ibody housing said inner tube and having axiallyspaced apart bearings slidably and sealingly engaged by said upper andlower wall portions to form a closed chamber containing air at.approximately atmospheric pressure and housing said downwardly facingshoulder, said inner tube also having upwardly and downwardly facingsurfaces exteriorly of the chamber and differing in area by theeffective area of said downwardly facing shoulder, a downwardly facingannular valve seat on 'the body through which the lower portion of theinner tube is movable lbetween a lower position in which the bottom tubeedge is projected below the valve seat and an upper position in whichsaid bottom tube edge is above said valve seat, spring means carried bythe body and active upwardly on the inner tube as the sole force biasingthe inner tube toward said upper position and ap valve pivoted on thebody for closing engagement with the body carried valve seat and througha swing path which is obstructed by said inner tube when its bottom edgeis below said valve seat.

2. A safety valve for subsurface 'installation in and control of a wellproduction string, including an outer tube for securement in and as partof a well production tubing string land having a downwardly facingannular valve seat and a flap valve pivotally mounted below said valveseat lfor upward and inward swing travel toward the valve seat, an innertube slidably fitted within the outer tube and shiftable between a firstposition in which the bottom of the inner tube is below said valve seatand obstructs the swing path of the flap valve and a second position inwhich the inner tube is wholly above said valve seat, spring meansinterposed between the tubes and exerting the only upward force on theinner tube, a self contained and sealed-oil gas chamber between saidtube confining gas under low pressure on the order of atmosphericpressure, an upwardly facing surface on the inner tube exteriorly ofsaid chamber and a downwardly facing surface on the tube exposed withinthe low pressure chamber.

3. A well tubing safety valve arranged to close upon tluid pressure dropto given valve downstream of the valve, comprising an outer tubularmember having a downwardly facing valve seat, a flap valve hinged to themember below said seat for swing movement toward and from engagementwith the seat, an inner tubular member slidably fitted within the outertubular member for relatively axial movement between a lower position inwhich a bottom portion of the inner member projects below said valveseat and an upper position in which said bottom portion is above thevalve seat, said members being arranged to provide a sealed chambertherebetween, said inner member having vertically offset peripheralportions and a downwardly facing shoulder intermediate said portions andenclosed within said sealed chamber and also having upwardly anddownwardly facing surfaces exteriorly of the chamber and differing inarea from one another and of which the larger surface area facesupwardly and is downstream and seated under compression against saidshoulder and said sealed chamber being free of fluid other than a gas atatmospheric pressure.

4. A well tubing safety valve comprising an outer tubular member forconnection in a well tubing string, a downwardly facing annular valveseat carried by said member, a valve movably mounted by said member forupward travel into closing engagement with said seat, an inner tubeslidably lfitted to said member for axial movement from one position inwhich the tube is wholly above said seat and another position in which atube portion is below said seat and blocks valve closing movement, meanson the tube responsive to tubing string fuid pressure downstream of thetube for urging the tube into its last mentioned position, spring meansinterposed under compression between the member and the tube for biasingthe tube in opposition to said downstream fuid pressure and a springenclosing chamber sealed at atmospheric pressure between the member andthe slidable tube.

5. A well tubing safety valve comprising an outer tubular member havinga valve seat thereon, a valve movably mounted on ythe member for travelinto closing engagement with the seat, an inner tube slidably fitted inthe outer member and movable between positions which respectively are inand out of the path of valve closing movement, elastic means interposedbetween the member and the tube and exerting yieldable force in thedirection to shift the tube out of said path, iiuid pressure sealsbetween axially spaced apart portions of the member and the tube andenclosing therebetween a sealed atmospheric pressure chamber, said tubehaving upwardly and downwardly facing surfaces equal in area to oneanother and a portion of the downwardly facing area being enclosedwithin the atmospheric pressure chamber and thereby limiting the area ofdownwardly facing surface exposed exteriorly of the chamber to less thanthe area of the upwardly facing surface.

6. A well tubing safety valve comprising an outer tubular member havinga valve seat thereon, a valve movably mounted on the member for travelinto closing engagement with the seat, an inner tube slidably fitted inthe outer member and movable between positions which respectively are inand out of the path of valve closing movement, elastic means interposedbetween .the member and the tube and exerting yieldable force in thedirection to shift the tube out of said path, said tube having upwardlyand downwardly facing surfaces exposed to well Huid flowing through thetube and which upwardly facing surface is exposed to well uid pressuredownstream of the tube and is of larger area than the downwardly facingReferences Cited by the Examiner UNITED STATES PATENTS Clark 137-498Moore 166--224 Raulins 137-460 Sizer 166-224 CHARLES E. OCONNELL,Primary Examiner. I. A. LEPPINK, Assistant Examiner.

4. A WELL TUBING SAFETY VALVE COMPRISING AN OUTER TUBULAR MEMBER FORCONNECTION IN A WELL TUBING STRING, A DOWNWARDLY FACING ANNULAR VALVESEAT CARRIED BY SAID MEMBER, A VALVE MOVABLY MOUNTED BY SAID MEMBER FORUPWARD TRAVEL INTO CLOSING ENGAGEMENT WITH SAID SEAT, AN INNER TUBESLIDABLY FITTED TO SAID MEMBER FOR AXIAL MOVEMENT FROM ONE POSITION INWHICH THE TUBE IS WHOLLY ABOVE SAID SEAT AND ANOTHER POSITION IN WHICH ATUBE PORTION IS BELOW SAID SEAT AND BLOCKS VALVE CLOSING MOVEMENT, MEANSON THE TUBE RESPONSIVE TO TUBING STRING FLUID PRESSURE DOWNSTREAM OF THETUBE FOR URGING THE TUBE INTO ITS LAST MENTIONED POSITION, SPRING MEANSINTERPOSED UNDER COMPRESSION BETWEEN THE MEMBER AND THE TUBE FOR BIASINGTHE TUBE IN OPPOSITION TO SAID DOWNSTREAM FLUID PRESSURE AND A SPRINGENCLOSING CHAMBER SEALED AT ATMOSPHERIC PRESSURE BETWEEN THE MEMBER ANDTHE SLIDABLE TUBE.